Apparatus for the continuous application of coating to strip material



April 9, 1963 A c BADGER 3,08

APPARATUS FOR IHE CONTINUOUS APPLICATION OF COATING TO STRIP MATERIAL 2 Sheets-Sheet 1 Filed Aug. 10, 1960 INVENTOR. Afton C. Badger BY '1) AM Aprxl 9, 1963 A. c. BADGER 3,084,662

APPARATUS FOR THE CONTINUOUS APPLICATION OF comm; TO STRIP MATERIAL 2 Sheets-Sheet 2 Filed Aug. 10, 1960 INVENTOR. Afton C. Badger Attorneys United States Patent 3,084,662 APPARATUS FGR THE CONTINUOUS APPLICA- THIN 0F COATING TO STRIP MATERIAL Afton C. Badger, Rte. 1, Box 546, Willits, Calif. Filed Aug. 10, 1960, Ser. No. 48,713 1 Claim. (Cl. 118--5tl) This invention relates generally to a system for applying surface-protecting coatings, and more particularly to a continuous system by which protective liquid coatings can be caused to penetrate the surface layers, including sides and ends, and to adhere to the surface of successive units of lumber and other strip material.

In the field of general construction, most application of surface coatings such as paint, varnish, stains, etc. is still done by handbrushing. However, application by dipping and spraying continues to gain favor because of the ease and rapidity of spread, thus saving labor, although these techniques result in the waste of some material. In general, none of these techniques is entirely satisfactory; handbrushing is tedious and time-consuming and does not always produce satisfactory results; spray painting frequently results in uneven application of material, causing sagging, orange peel or other undesirable effects on the surface; dip application is subject to gravity effects causing excess paint to form puddles or ridges which delay drying and give a poor appearance.

There has been some progress, particularly in the manufacture of prefabricated building units, in the application of surface coatings under controlled factory conditions. However, such techniques are not adapted to the coating of building materials in elongated or strip form, such as lumber and similar items.

In general, it is an object of the present invention to provide a system for the continuous application of surfaceprotecting coatings which solves the problems inherent in former coating techniques, and which effects a continuous absorption of protective liquid coatings into the surface layers and onto the surface of successive units of strip building materials.

A further object of the invention is to provide a continuous coating system of the above character adapted to achieve a uniform coating of units of lumber, such as boards, and which functions to remove all of the excess coating material from the surface of the lumber undergoing treatment.

Another object of the invention is to provide a system of this character which acts to coat successive units of material with a high degree of efiiciency and a minimum waste of coating material.

Another object of the invention is to provide a continuous coating system of this character which produces coated units having improved drying characteristics.

Other objects and advantages of the present invention will be apparent from the following description of an exemplary embodiment and from the drawings, in which:

FIGURE 1 is a view in perspective of apparatus embodying the invention;

FIGURE 2 is a view in vertical section through the apparatus of FIGURE 1;

FIGURE 3 is a view in side elevation thereof;

FIGURE 4 is an exploded perspective view showing details of guide means associated with the apparatus;

FIGURE 5 is a schematic view in elevation, showing a coating system embodying my invention; and

FIGURE 6 is a view like FIGURE 5 showing a modified system in accordance with the invention.

Generally stated, my invention makes use of a chamber which is closed to the atmosphere, and which contains a quantity of a surface-protecting coating such as paint, lacquer, stain, varnish, etc. Inlet and outlet means 3,684,662 Patented Apr. 9, 1963 are provided on opposite sides of the chamber, preferably in horizontal alignment, and generally conforming to the cross section of units of lumber or otherv strip material being fed to the system. Above the level of coating material within the chamber, I provide positive acting suction means which functions not only to seal the inlet and outlet openings against outward flow of coating material about lumber positioned therein, but also to remove all excess coating material not actually bound to the lumber or other units undergoing treatment.

Referring to the embodiment of my invention illustrated in the drawing, 10 indicates an airtight chamber or tank adapted to contain a quantity of coating material 12. An access opening 14 is provided in the top of the tank for the introduction of the coating liquid, and is provided with a closure 16 so as to be closed to the atmosphere. An inlet 18 is provided near the bottom of the tank for the introduction of units of strip material into the tank in endwise abutting relation. An outlet 20 is similarly positioned on the side of the tank opposite from the inlet so as tobe substantially in horizontal alignment with the inlet. A drain 22 may also be provided at the bottom of the tank to facilitate cleaning.

Referring to FIGURE 4, the inlet 18 is seen to comprise an opening 24 in the wall of the tank which is partially closed by sealing and guiding members conforming to the cross section of the strip material being introduced to the tank. These members include a backup plate 26, a gasket 2d offelt or other suitable absorptive material, and a guide attachment 30 including the tapered inlet guide 32. The tank opening 24 is dimensioned to receive the largest unit of stock to be coated. In contrast the openings 34, 36 and 38 of the sealing and guide units are dimensioned to a particular stock size, with a set of the members 26, 28 and 30 being provided to accommodate each size and shape of stock to which the system is adapted.

The outlet 20 can be constructed similarly to the inlet. Preferably the guide attachment 3% of the outlet is positioned within the tank, whereas the gasketing 28 is positioned externally of the tank between a pair of plates 26 as illustrated in FIGURE 2. As will be understood, the inlet assembly 18 functions to positively direct units of strip material, indicated at 8 through the chamber to the interior guide 30 of the outlet assembly 20.

Referring to FIGURE 2, the space 40 above the level of the coating material in the treatment chamber is connected to an outlet suction line 4-2 by means of the aperture 44. The suction induced in the line 42 is sufficient during operation to cause a continuous flow of air into the chamber about the periphery of the strip material positioned within the inlet and outlet openings 18 and 20. This inflow of air serves to seal the inlet and outlet openings 18 and 20. It also functions to remove any liquid coating not actually bound to the surface of strip material leaving the system through the outlet 20 (i.e., by absorption, or by absorption onto the surface of the material). The coating action is therefore, highly efficient in that it permits continuous penetration of the protective coating into the material undergoing treatment, while simultaneously preventing excess thickness from building up on the exterior surfaces of the stock to cause paddling, sagging or other deterrents to uniform drying or satisfactory appearance of the final products.

A system of apparatus useful in carrying out my invention is illustrated in FIGURE 5. 50 represents a feed mechanism including upright guides 52 to receive the strip material and a chain feed 54 adapted to frictionally engage the lowermost unit 8. The stock delivered by the feed mechanism is immediately grasped and positively charged to the tank 10 by a pair of rollers 56. These assasae 3 rollers frictionally engage the sides of the stock to exert a constant continuous pressure urging the stock through the chamber to the outlet 20. Preferably the chain feed 54 advances the stock at a rate slightly faster than the rollers 56, thereby to prevent any gaps between abutting ends of the stock such as might lose the suction forces about the periphery of the stock in the inlet =13. Any suitable means such as the motor 58, speed reduction unit 60, and gear train 62 may be employed to power the rollers 56 and chain feed 54.

The stock passing through the tank is immediately subjected to the combined treating effects of the coating material 12 and the suction induced air currents created by the positive action blower unit 64 (illustrated in FIGURE 5 as being of the centrifugal type). Preferably a surge tank or other suitable means 66 is provided in the line 42 to accommodate any accidental discharge of coating material from the interior of the tank, for example, due to failure of the feeding mechanism. Any liquid entrained in the suction line impinges against the baffle 68, and may be withdrawn through the discharge outlet 70.

The operation of the apparatus just described can be briefly summarized as follows: Units of stock 8 (e.g. lumber, plaster board, strip metal, etc.) are positioned within the uprights 52, with the lowermost unit being fed manually through the rollers 56 and the inlet opening 18 until its leading end engages within the outlet 20. The tank 10 is now filled with coating material through the access opening 14. The closure 16, which is machined to a close fit, is replaced and is subsequently held tight by atmospheric pressure induced by the blower unit. The blower 64 is now energized to create forces in suction about the periphery of the stock in the inlet and outlet openings 18 and 20. The volume of air exhausted through the blower and the degree of suction required to achieve the desired forces in suction about the workpieces, will vary somewhat with the type of material being treated, the viscosity of the protective coating liquid, and the amount of coating to be deposited on the surface of the workpiece. By way of illustration, a centrifugal blower of the type illustrated will develop pressures ranging from about 0.5 to 10 pounds per square inch, and has been found to operate satisfactorily at pressures somewhat below about 5 pounds per square inch. The motor 58 is now energized to feed a continuous supply of stock through the tank 10 and through the coating material contained therein. The positive forces in suction created by the blower not only prevents the coating liquid from flowing out of the coating chamber, but also draws away all liquid not actually bound to the surface of treated stock exiting through the outlet 20. As a result of this treatment, coating liquid is absorbed into the surface layers, including sides and ends, and onto the outer surface of each workpiece; thereafter excess coating liquid is stripped from the stock by a positive wiping action of the gasketing in the outlet opening, and by the forces in suction.

Many different embodiments and applications of my system will suggest themselves to those in this art, without departing from the spirit and scope of the invention.

By way of specific illustration, FTGURE 6 represents the use of a positive pressure system to exhaust gases from above the surface of the coating material. In this type of apparatus, I prefer to employ a cycloidal or gear type of blower 70, due to the capacity of this type of equipment to exhaust large volumes of gas against relatively high pressures. The exhaust from the blower exerts a continuous and constant pressure on coating material contained in a reservoir 72, which flows through return line 74 and a suitable throttling valve 76 into a lower portion of the treating tank 10. The function of the valve 76 is to insure that the suction pulled by the blower through the line 78 is at all times greater than the rate of feed through the line 74 thus producing an effect similar to that described in connection with the embodiment of FIGURE 5. Many additional variations are of course possible, and it should be understood that the disclosures and description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

In a system for the continuous absorption of a protective liquid coating into the surfaces, including sides and ends of successive units of absorptive strip material: a coating chamber of substantial vertical dimensions and closed to the atmosphere, said coating chamber containing a substantial head of liquid coating material, means forming an inlet into said chamber conforming to the cross section of said strip material, means forming an outlet from said chamber likewise conforming to the cross section of said strip material, said inlet and outlet means being on opposite sides of said chamber, substantially in horizontal alignment with one another, and located at a level in the chamber where substantial hydrostatic pressure is obtained, and means acting continuously above the level of liquid coating material in said chamber to exert forces in suction sufiicient to induce a continuous flow of air into the chamber about the periphery of said strip material positioned within said inlet and outlet and upwardly through coating liquid in said chamber, said flow of air serving to seal the inlet and outlet and to remove from the strip material leaving the system any liquid coating not actually bound to the surface of said material there being absorptive sealing and wiping members positioned within each of said inlet and outlet means, said members each having a central opening conforming to the cross-section of the strip material being treated and of dimensions no greater than said strip material whereby excess coating is wiped from. said material while air is permitted to enter said chamber through said sealing and wiping means.

References Cited in the file of this patent UNITED STATES PATENTS 1,263,858 Cole Apr. 23, 1918 2,255,436 Olson Sept. 9, 1941 2,329,378 Kuehner Sept. 14, 1943 2,331,983 Kaiser Oct. 19, 1943 2,540,006 Otto Jan. 30, 1951 2,649,757 Diamond Aug. '25, 1953 

